It is the fact that the electrons cannot all get on top of each other that makes tables and everything else solid. Richard Feynman
According to Pauli, not only do electrons each insists on taking up a finite amount of room, they have to have their own rooms. Thus, the quantum Hall problem may be described as a sort of housing crisis, or as the problem of assigning office space at the Institute for Theoretical Physics to visitors who do not want to share offices. http://xxx.lanl.gov/pdf/cond-mat/9501022v2